A. Field
The present invention concerns a method for manufacturing a filling material.
B. Related Technology
In particular, the invention concerns a method for manufacturing filling materials with varying degrees of hardness and varying thicknesses going from springy filling materials for mattresses, pillows and parts of furniture to sit or to lie on, to relatively tough filling material for sandwich panels, for example for the car and aeronautical industry.
A known method for manufacturing a filling material for mattresses, pillows and the like is described in international patent application WO 03/003878.
This method consists in providing strips of synthetic or natural foam and in making incisions in them, after which these strips are rolled up so as to form a cylinder whereby their longitudinal side edges are fixed to one another, for example by means of gluing. Due to this imposed shape, the cuts are deformed in such a manner that they are pulled open or opened wide on the outside of the cylinder, such that cavities are formed which are mutually separated by ribs. These cavities narrow towards the centre of the cylinder.
By arranging a number of cylinders in a bundle and by mutually gluing these cylinders together, in particular by providing a glued joint between the leaning ribs, and by subsequently cutting this bundle in a direction crosswise to the axis of the above-mentioned cylinders, layers or plates are obtained so to say which are built of cylindrical or ring-shaped bodies which are glued together and which can be compressed in an elastic manner and therefore will be called foam springs further on.
A problem arising with this method is that the number of cylinders which can be mutually connected is restricted. Indeed, too large a number of mutually connected cylinders results in a heavy, cumbrous and unmanageable chunk.
Moreover, due to the heavy weight of larger layers, the glued joints between the leaning ribs of the foam springs will give way while these layers are being manipulated.
Also, the method as discussed is applied in particular for manufacturing small layers or plates of filling material.
Another problem which arises with the method for manufacturing a filling material for mattresses, pillows and the like, as described in WO 03/003878, is that thin layers of for example 3 cm or 4 cm cannot be manufactured in a consistent and unalterable manner, since the knife deforms the free ends of the bundled cylinders somewhat too much, and there is no space available to hold the far ends in an efficient manner during the cutting.
Thus cutting thin layers results in layers with unwanted variations in relation to the aimed shape.
However, the thin layers are ideal for producing an alternative filling material which can be used to replace the conventional comfort layers in mattresses, furniture to sit on, car seats, packings, etc. Among the advantages can be mentioned the weight-saving which can amount to over 20%, the improved air permeability, a better shock absorption and savings on raw materials of up to more than 25%.